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E. F. Gramsbergen

Bio: E. F. Gramsbergen is an academic researcher from Solid State Physics Laboratory. The author has contributed to research in topics: Liquid crystal & Phase transition. The author has an hindex of 5, co-authored 7 publications receiving 349 citations.

Papers
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Journal ArticleDOI
TL;DR: A review of the wide variety of predictions that results from a Landau-type of description of the nematic-isotropic phase transition is given in this paper, which includes a discussion of the nature of the order parameter and of the various types of possible phases.

291 citations

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TL;DR: In this article, the birefringence of mixtures of homologues from the terminally non-polar series of p,p′-dialkylazoxybenzenes has been studied.
Abstract: The birefringence of mixtures of homologues from the terminally non-polar series of p,p′-dialkylazoxybenzenes has been studied. The birefringence is used as a probe of the orientational order parameter, which is coupled to the translational (smectic) order parameter. The tricritical nematic to smectic-A point which results from this coupling is found at a McMillan ratio TAN/TNI= 0.977. This is similar to the values reported for terminally polar systems and is higher than predicated by theory. The critical exponent for the variation of the order parameter across the SA–N phase transition obeys the expected trend.

28 citations

Journal ArticleDOI
TL;DR: In this article, the X-ray reflectivity form the surface of a liquid crystal with terminally polar (cyano substituted) molecules has been studied using a high-resolution triple-axis Xray spectrometer in combination with a synchrotron source.
Abstract: The X-ray reflectivity form the surface of a liquid crystal with terminally polar (cyano substituted) molecules has been studied using a high-resolution triple-axis X-ray spectrometer in combination with a synchrotron source. It is demonstrated that at the surface of the smectic A1 phase a few antiferroelectric double layers develop that can be distinguished from the bulk single layer structure. A model is developed that separates the electron density in a contribution from the molecular form factor, and from the structure factor of the mono- and the bilayers, respectively. With only a few adjustable parameters it accounts for the rather complex observed reflection curve. It shows that (i) the first molecular layer has tails up rather than heads up, (ii) the smectic order parameter of the first mono- and bilayer is saturated, (iii) the antiferroelectric bilayering does decay rather abruptly and not exponentially Etude RX de la surface d'un cristal liquide pres de la transition nematique-smectique A1. Developpement en surface de quelques doubles couches antiferroelectriques qui peuvent etre distinguees de la structure en simples couches du materiau massif

25 citations

Journal ArticleDOI
TL;DR: In this article, the elastic constants in the nematic phase of some molecules with a curved (banana-like) molecular shape have been investigated and shown to have quite normal values as compared with similar non-curved molecules.

12 citations


Cited by
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Journal ArticleDOI
B Jerome1
TL;DR: In this paper, a review focusing on nematic liquid crystals is presented, where three main kinds of effects can be distinguished: the perturbation of the liquid crystalline structure close to the surface, the bulk liquid crystal structure is recovered with an orientation which is fixed by the surface and critical adsorption or wetting can occur at surfaces.
Abstract: As their name indicates, liquid crystals simultaneously exhibit some characteristics common to both ordinary isotropic liquids and solid crystals. This ambivalence is also found in the effects of surfaces on these systems which lead to a great diversity of phenomena. These phenomena are reviewed focusing on nematic liquid crystals which have the simplest structure among the many existing types and which have been the most extensively studied. Three main kinds of effects can be distinguished. The first concerns the perturbation of the liquid crystalline structure close to the surface. Beyond this transition region, the bulk liquid crystalline structure is recovered with an orientation which is fixed by the surface: this phenomenon of orientation of liquid crystals by surfaces is the so-called anchoring. Finally, close to bulk phase transitions, critical adsorption or wetting can occur at surfaces as is also seen in isotropic systems.

754 citations

Journal ArticleDOI
TL;DR: In this article, the physics of colloidal dispersions in nematic liquid crystals is reviewed and three possible structures are identified and discussed in detail; the dipole, the Saturn-ring and the surface-ring configuration.

579 citations

Journal ArticleDOI
TL;DR: A comprehensive overview of phase transition studies can be found in this article, where the authors identify the essential key concepts and points of difficulty associated with the study of phase transitions and discuss the most widely used experimental techniques for measuring these transition properties.

308 citations

Journal ArticleDOI
TL;DR: In this paper, a general expression for the kinematic scattering cross-section of X-rays and neutrons impinging on an arbitrary interfacial structure is derived based on the distorted wave Born approximation.

161 citations